The present invention relates to a handle-operating mechanism for a circuit breaker that is provided with a rotary operating handle and is implemented in a molded-case circuit breaker or the like.
First, a conventional configuration of a circuit breaker provided with the rotary operating handle referred to above is shown in FIGS. 4 to 6(b). First, in FIG. 4, reference numeral 1 denotes a breaker case; reference numeral 2 denotes a breaking section for a main-circuit contact; reference numeral 3 denotes a contact opening-and-closing mechanism section; reference numeral 4 denotes an overcurrent tripping device; reference numeral 5 denotes a rotary operating handle installed on a top surface of the case 1; reference numeral 6 denotes a gear mechanism linking the operating handle 5 to the contact opening-and-closing mechanism section 3; and reference numeral 7 denotes an attachment, such as an auxiliary switch, an alarm switch, a voltage tripping device or an undervoltage tripping device, of the circuit breaker that is optionally installed in the case 1.
Here, the gear mechanism 6 is formed of a combination of a rotating gear (driving gear) 8 connected to a shaft of the operating handle 5, and a toggle gear 9 attached to the contact opening-and-closing mechanism section 3 so as to cross the rotating gear 8, as shown in FIG. 5. When the operating handle 5 is rotated from an OFF position to an ON position, a toggle link mechanism 3a in the contact opening-and-closing mechanism section 3 is pivoted via the gear mechanism 6 to turn on the main-circuit contact via an opening-and-closing lever (not shown). Conversely, when the operating handle 5 is rotated from the ON position to the OFF position, the toggle link mechanism 3a and an opening-and-closing spring 3b work together to open the main-circuit contact. When the overcurrent tripping device 4 is activated to perform a tripping operation in order to open the main-circuit contact, the operating handle 5 moves from the ON position to a TRIP position.
Further, FIGS. 6(a) and 6(b) show the conventional structure of the above-described gear mechanism 6. The rotating gear 8 has teeth 8a meshing with the toggle gear 9, and is coupled to a shaft 5a of the operating handle 5 in such a manner as to fit thereon. On the other hand, the toggle gear 9 is linked to the above-described toggle link mechanism by assembling a shaft thereof to the contact opening-and-closing mechanism section 3 so that the shaft crosses the rotating gear 8; the teeth of the toggle gear 9 mesh with the teeth 8a of the rotating gear 8. A return spring 10 urges the operating handle 5 in the direction of the OFF position.
The molded-case circuit breakers can be provided with various optional attachments. In particular, in an attachment, such as an undervoltage tripping device with an early-operation contact that detects an abnormal voltage to trip the circuit breaker, when the handle is operated to turn on the circuit breaker, the contact within the attachment must be closed to transmit a signal before the contact opening-and-closing mechanism section performs a turn-on operation.
Thus, in a conventional circuit breaker provided with a tumbler-type operating handle, an auxiliary handle that is withdrawn from the undervoltage tripping device with the early-operation contact is linked to the operating handle of the breaker main body, and the built-in contact of the undervoltage tripping device is turned on while the operating handle is being switched from the OFF position to the ON position.
On the other hand, the following is required to allow the above-described circuit breaker provided with the rotary operating handle to accommodate the above-described undervoltage tripping device (attachment) with the early-operation contact. Namely, an idle stroke must be set such that when the circuit breaker is turned on, the operating handle 5 shown in FIG. 6(a) runs with idle or play after the handle 5 has started its rotation from the OFF position and before the toggle gear 9 of the contact opening-and-closing mechanism section 3 is driven, so that, during this stroke, the built-in contact of the attachment can be closed to transmit the signal. Moreover, the handle operation mechanism must provide a function for fixing the operating handle in the ON position after the main-circuit contact has been turned on.
The present invention has been made in view of the above points, and it is an object of the invention to provide a handle-operating mechanism for a circuit breaker that is operative when the circuit breaker is turned on, to allow a signal to be transmitted to an attachment, such as an undervoltage tripping device with an early-operation contact, before a contact opening-and-closing mechanism section of the circuit breaker operates.
Further objects and advantages of the invention will be apparent from the following description of the invention.
To attain the above object, the present invention provides a handle-operating mechanism for a circuit breaker comprising a rotary operating handle manually operated to open and close a main-circuit contact of a circuit breaker. The operating handle and a contact opening-and-closing mechanism section are linked together via a rotating gear connected to the operating handle and via a toggle gear provided in the contact opening-and-closing mechanism and meshing with the rotating gear. In the handle-operating mechanism, a clutch gear is interposed between the operating handle and the rotating gear, and an idle stroke is set in which, when the circuit breaker is turned on, the operating handle runs idly after the operating handle has started rotation and before the rotating gear drives the toggle gear of the contact opening-and-closing mechanism section.
Further, the above-mentioned clutch gear is set such that a tooth thereof meshes with the toggle gear while overlapping a tooth of the rotating gear in a manner such that the clutch gear is coupled to the rotating gear. The clutch gear is combined with a return spring and connected to the operating handle.
With the above configuration, when the rotary operating handle is manually operated to turn on the circuit breaker, it runs idly during the idle stroke that starts when it starts rotation and ends when the clutch gear is linked to the rotating gear to drive the toggle gear of the contact opening-and-closing mechanism section. Consequently, during this stroke, the signal can be transmitted to an attachment, such as an undervoltage tripping device with an early-operation contact, for detecting an abnormal voltage at the main circuit, before the opening-and-closing mechanism section of the main-circuit contact operates.
Furthermore, after the main-circuit contact has been turned on, the toggle gear linked to the toggle link of the contact opening-and-closing mechanism section is held and bound in this position with the teeth of the rotating gear and the clutch gear meshing therewith, so that the operating handle is fixed in the ON position without any play. On the other hand, when the main-circuit contact is opened, the operating handle rotates synchronously with the rotating gear, in contrast to the turn-on operation. Once the tooth of the clutch gear is disengaged from the toggle gear, the rotating gear remains in the same position, and the spring force of the return spring is exerted to cause the operating handle to run idly together with the clutch gear to return to the OFF position.